Various applications may require motion of rotating or translating components to be retarded or produced quickly with minimal energy. In one example, rotating shafts or axles of a vehicle drivetrain may be connected or disconnected in order to shift a vehicle into a two-wheel drive mode (e.g., 4×2 mode) or a four-wheel drive mode (e.g., 4×4 mode). Specifically, vehicles may employ disconnect assemblies with a clutch that can move to connect or disconnect two rotatable components such as two shafts. The disconnect assemblies can be placed in a variety of areas in the drivetrain of a vehicle, including at the wheel ends, at one or more axles, or along one of the drive shafts. Through the use of disconnect systems, vehicles can be made more versatile by having the ability to switch between different drive modes depending on the driving conditions and operator desire.
In some powertrain disconnecting systems, vacuum directed from the vehicle engine is used as the motive or actuating force that powers the disconnecting systems. In particular, the disconnecting system actuators may be powered by the vacuum. In many systems, the vacuum is directed via a passage from the intake manifold of the gasoline-fueled engine. Due to this, the vacuum level, or amount of force or pressure available from the vacuum, may vary as engine throttle settings change along with engine load. For many engine systems, the vacuum level (amount of pressure available) may be limited or vary due to the effects of altitude. Furthermore, temperature changes can also cause pressure fluctuations in the vacuum level, thereby causing fluctuations in movement of the disconnect actuator which may result in undesirable movement of disconnect components such as the diaphragm and clutch components. Additionally, in some vehicles vacuum may not be readily available since various vehicle accessory systems may not be powered by vacuum, or the vehicle may be designed to remove engine intake connections such as vacuum lines in order to enhance engine control and performance. Finally, vacuum-powered powertrain disconnect systems are becoming less desirable with more advanced vehicle design. As such, powertrain disconnect systems are needed that are powered by sources other than vacuum and feature designs conducive to modern vehicle systems.
Additionally, in other applications, such as other clutching or braking systems, motion may need to be retarded or produced quickly. In one example, electromagnetic coils may be utilized in wet plate clutches or locking differentials. In these systems, the coil is stationary and upon energization of the coil, an armature is attracted to and translates towards the coil. The motion of the armature then causes a desired action which may be to clutch against another component. Typically, there is always an air gap between the coil and armature which causes the energy demand to be very high to produce the desired movement via the armature. This may result in high energy usage and potential degradation to the electromagnetic coil assembly components over time. The inventors herein have recognized the above issues and developed various approaches to address them.
Thus in one example, the above issues may be at least partially addressed by a method of operating an electromagnetic coil assembly, comprising: responsive to energization of an electromagnetic coil of the electromagnetic coil assembly, translating the electromagnetic coil along a central axis of the electromagnetic coil assembly toward a magnetic armature while maintaining the armature fixed along the central axis. As the coil translates toward the armature, an air gap between the coil and armature is reduced. Thus, by having the coil translate and close the air gap, less energy may be required to clutch the coil against the armature and therefore effect movement of the armature or secondary mechanisms coupled with the armature. Further, by translating the coil toward the armature while maintaining the armature fixed along the central axis, more precise axial movement of the assembly components may be achieved.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.